Proceedings of the National Academy of Sciences · 1979 · 148 citations · 21 references
Life SciencesMicrobiologyMolecular BiologyGene RegulationTranscriptionTranscriptional RegulationBacterial Gene RegulationPromoter RecognitionPromoter RegulationTranscription FactorsTranscription Start SitesTranscriptional Regulation In ProkaryotesBacterial PromotersCamp-responsive Gene ExpressionCyclic Nucleotide Binding ProteinsDna Binding SitesDna Recognition SequencesEscherichia ColiInteraction Site MappingLactose Operon Regulation
Cyclic AMP (cAMP) and its receptor protein (CRP) have a dual role in the regulation of the two promoters that control the galactose (gal) operon of Escherichia coli. One promoter, P1, requires cAMP-CRP for activity; the other, P2, is inhibited by these factors. We have examined the interactions site of cAMP-CRP on gal DNA by using two types of protection experiments, involving DNase digestion and methylation by dimethyl sulfate. Our results indicate that cAMP-CRP binds to gal DNA in a segment located between 50 and 24 base pairs preceding the P1 start point for transcription. Although the location of the cAMP-CRP interaction site is clearly different in gal and lac DNA, comparison of the DNA sequences suggests a similar recognition sequence. The location of the cAMP . CRP-binding site in gal further suggests that protein-protein interactions between RNA polymerase and cAMP . CRP play an important role in transcription initiation at the gal and possibly other cAMP-dependent promoters.
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